1. Field of the Invention
The present invention relates to a conductive composition used for a conductive material of an electronic component, and to a ceramic electronic component.
2. Related Background Art
It has proceeded to make a thin-layered dielectric and a thin-layered electrode corresponding thereto in order to comply with requirements of miniaturization and capacity enlargement of a capacitor.
There is a tendency that a metal powder comprised in an electrode paste used to form an electrode is made fine when making the thin-layered electrode. However, when the metal powder is made fine, a surface energy per unit volume increases and thereby, a sintering initiation temperature of the electrode is lowered. Thus, the difference in the sintering initiation temperatures between the electrode and the dielectric is increased. As a result, a crack or a de-lamination easily occurs, and reliability of the capacitor is lowered.
In order to suppress occurrence of the crack or the de-lamination, it is proposed to increase an amount of a compatible material added to the electrode paste (for example, refer to Japanese Patent Application Laid Open No. HEI 7-201223). The compatible material means such ceramics that have the same composition as that of the dielectric or do not deteriorate properties of the dielectric. In addition, the sintering initiation temperature of the compatible material is higher than that of the metal powder used for the electrode. The sintering initiation temperature of the electrode can approach that of the dielectric by increasing the amount of compatible material.
However, when the amount of compatible material is increased, a metal component per unit volume of the electrode is reduced. Thereby, continuity of the conductive material of the electrode is hindered, and the electrode effective area in the capacitor decreases. This means that the capacitance becomes small even in the same capacitor design.
On the other hand, a ceramic multilayer insulator also requires miniaturization and reduction of loss. In order to miniaturize the insulator, it is necessary to narrow the line width of the electrode and thin the thickness thereof. However, in the case of the above-mentioned configuration, the loss of the electrode line increases, and it becomes difficult to attain the low loss performance. Similarly, in the case of the insulator, when there is a big difference in the sintering initiation temperatures between the electrode and the ceramics, the crack or the de-lamination occurs and the reliability is lowered.
Hence, a study has been done in order to solve the aforementioned problem. For example, Japanese Patent Application Laid Open No. HEI 6-290985 discloses a conductive composition in which an oxide of at least one element selected among magnesium, zirconium, tantalum and rare earth element is added to a conductive paste made of the metal powder of nickel powder. In the above-mentioned publication, it is described that a generation of the crack can be prevented because an expansion of the nickel electrode is suppressed in a baking step by use of the above-mentioned composition.
Moreover, Japanese Patent Application Laid Open No. 2000-340450 discloses the conductive composition in which nickel powder coated with a magnesium oxide layer is compounded. The above-mentioned publication describes that by use of such method, a generation of the crack and the de-lamination can be suppressed by increasing the sintering initiation temperature of the electrode, and a moisture resistance load property can be improved to make a thin layer of the internal electrode.